Hollow composite structures have been manufactured by braiding or winding fibers, filaments or tapes (hereinafter fibers) on mandrels. The fibers, are coated with resin or other binders by dip tanks, spraying or other coating methods.
The coating devices and methods used in the past have not produced consistant quality structures because the coatings applied were not uniform. The poor quality was particularly evident when the fibers were moving or rotating about the mandrel in a braiding or winding application.
To overcome the deficiencies of the prior art coating methods and devices, the inventive impregnation ring was designed for a uniform application of resin or binder to the fibers. The inventive impregnation ring can coat roving fibers received from any point on its 360.degree. circumference. The inventive ring can accommodate hot melt thermoplastic and thermoset resin systems as well as resin systems contained in solvents.
The impregnation ring is hollow and has a circumferential slot for resin distribution. A ring shaped elastomeric or steel gasket, located inside the hollow impregnation ring, controls the slot opening. If a large amount of resin is necessary, two or more impregnation rings may be used to coat the fibers. In the preferred embodiment as depicted therein, the resin pressure in hollow ring controls the position of the ring shaped gasket located within the impregnation ring and its engagement of the circumferential slot. The slot opening controls the flow of the resin from the ring onto the fibers which are drawn across the slot for coating.
In cases where the mandrel rotates and the fibers follow a fixed path, the impregnation ring can have a discontinuous or segmented slot. The inner ring shaped gasket seal may be segmented or continuous and seal the segmented slots. This segmented ring will allow resin to be delivered only in that portion of the 360.degree. pattern where fibers cross the ring.
The segmented slot openings could be adjustable and indexed for different fiber winding requirements.